The fate of pluripotent stem cells is tightly controlled during early embryonic development. Both the derivation and the maintenance of embryonic stem cells (ES cells) in vitro depend on feeder cell-derived growth factors that are largely unidentified. To dissect the mechanisms governing pluripotency, we conducted a screen to identify factors that are produced by mouse embryonic fibroblast STO cells and are required to maintain the pluripotency of ES cells. One of the factors is bone morphogenetic protein 4 (BMP4). Unexpectedly, the major effect of BMP4 on the self-renewal of ES cells is accomplished by means of the inhibition of both extracellular receptor kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways, and inhibitors of ERK and p38 MAPKs mimic the effect of BMP4 on ES cells. Importantly, inhibition of the p38 MAPK pathway by SB203580 overcomes the block in deriving ES cells from blastocysts lacking a functional Alk3, the BMP type IA receptor. These results uncover a paradigm for BMP signaling in the biology of pluripotent stem cells.E mbryonic stem cells (ES cells) are able to form all cell types of the body by following normal embryogenesis (1-3). The pluripotency of ES cells has attracted great attention for their potential use in tissue and cell therapy. However, the molecular and developmental mechanisms controlling pluripotency and differentiation of ES cells are largely unknown, and only a very limited number of genes has so far been shown to affect the fate decisions of inner cell mass (ICM) or ES cells. These genes include Oct4, Fgf4, H2az, Foxd3, Nanog,.Growth factors required for ES cell self-renewal are usually provided by feeder cells, or exogenously (13). Leukemiainhibiting factor (LIF) and its close relatives are the known propluripotency factors for mouse ES cells. It is unclear how many other growth factors or signaling pathways are required for the self-renewal of ES cells. To address these questions, we set out to identify such factors that affect the self-renewal of ES cells. To accomplish this, we isolated and screened sublines of the mouse embryonic fibroblast STO cells for their ability to support the self-renewal of ES cells by using Oct4-GFP as a convenient marker of pluripotency (14-16). By this approach in combination with gene expression profiling, we have identified bone morphogenetic protein 4 (BMP4) as part of the extracellular propluripotency cues. Also, our studies show that BMP4 and LIF have synergistic effect in teratoma formation. Moreover, a number of genes differentially expressed in ES cells cultured with or without exogenous BMP4 have been identified.One of these differentially expressed genes, X-linked inhibitor of apoptosis (Xiap), is expressed at higher levels in ES cells cultured in the presence of exogenous BMP4 than in its absence. XIAP has been implicated in connecting the type I receptors of BMPs and TGF-␤s with the mitogen-activated protein kinase (MAPK) p38 pathway (17)(18)(19)(20). Contrary to previous findings in which BMP signaling up-r...

Atherosclerosis (AS) is chronic inflammation in response to lipid accumulation. MicroRNA-155 (miR-155) is being increasingly studied to evaluate its potential as diagnostic biomarkers and therapeutic targets in many diseases. However, delineating the role of miR-155 in AS remains difficult. Here, we detected constitutive expression of several microRNAs (miRNAs) possibly associated with cardiovascular disease in foam cells and clinical specimens from patients with AS. Among them, we found that the level of miR-155 in foam cells was the most significantly elevated in a dose- and time-dependent manner. In addition, the expression of miR-155 was elevated in the plasma and plaque of patients with AS. We also reported for the first time that miR-155 targets calcium-regulated heat stable protein 1 (CARHSP1), which regulates the stability of tumor necrosis factor alpha (TNF-α) mRNA. Furthermore, we investigated the mechanism by which the miR-155 level is elevated. miR-155 upregulation is due to transcriptional regulation by nuclear factor (NF)-κB, which is activated by the inflammatory factor TNF-α. In summary, increased miR-155 relieves chronic inflammation by a negative feedback loop and plays a protective role during atherosclerosis-associated foam cell formation by signaling through the miR-155–CARHSP1–TNF-α pathway.

Sirtuins (SIRTs), NAD+-dependent class III histone deacetylases (HDACs), play an important role in the regulation of cell division, survival and senescence. Although a number of effective SIRT inhibitors have been developed, little is known about the specific mechanisms of their anticancer activity. In this study, we investigated the anticancer effects of sirtinol, a SIRT inhibitor, on MCF-7 human breast cancer cells. Apoptotic and autophagic cell death were measured. Sirtinol significantly inhibited the proliferation of MCF-7 cells in a concentration-dependent manner. The IC50 values of sirtinol were 48.6 µM (24 h) and 43.5 µM (48 h) in MCF-7 cells. As expected, sirtinol significantly increased the acetylation of p53, which has been reported to be a target of SIRT1/2. Flow cyto-metry analysis revealed that sirtinol significantly increased the G1 phase of the cell cycle. The upregulation of Bax, downregulation of Bcl-2 and cytochrome c release into the cytoplasm, which are considered as mechanisms of apoptotic cell death, were observed in the MCF-7 cells treated with sirtinol. The annexin V-FITC assay was used to confirm sirtinol-induced apoptotic cell death. Furthermore, the expression of LC3-II, an autophagy-related molecule, was significantly increased in MCF-7 cells after sirtinol treatment. Autophagic cell death was confirmed by acridine orange and monodansylcadaverine (MDC) staining. Of note, pre-treatment with 3-methyladenine (3-MA) increased the sirtinol-induced MCF-7 cell cytotoxicity, which is associated with blocking autophagic cell death and increasing apoptotic cell death. Based on our results, the downregulation of SIRT1/2 expression may play an important role in the regulation of breast cancer cell death; thus, SIRT1/2 may be a novel molecular target for cancer therapy and these findings may provide a molecular basis for targeting SIRT1/2 in future cancer therapy.

Stem cell therapy is an emerging therapeutic modality in the treatment of stroke. We assessed the safety and feasibility of the cotransplantation of neural stem/progenitor cells (NSPCs) and mesenchymal stromal cells (MSCs) in patients with ischemic stroke. Eight patients were enrolled in this study. All patients had a hemisphere with infarct lesions located on one side of the territories of the cerebral middle or anterior arteries as revealed with cranial magnetic resonance imaging (MRI). The patients received one of the following two types of treatment: the first treatment involved four intravenous injections of MSCs at 0.5 × 10 6 /kg body weight; the second treatment involved one intravenous injection of MSCs at 0.5 × 10 6 /kg weight followed by three injections of MSCs at 5 × 10 6 /patient and NSPCs at 6 × 10 6 /patient through the cerebellomedullary cistern. The patients' clinical statuses were evaluated with the National Institutes of Health Stroke Scale (NIHSS), the modified Rankin Scale (mRS), and the Barthel index (BI). Six patients were given four cell transplantations. The most common side effect of stem cell transplantation in these six cases was low fever that usually lasted 2-4 days after each therapy. One patient exhibited minor dizziness. All side effects appeared within the first 2-24 h of cell transplantation, and they resolved without special treatment. There was no evidence of neurological deterioration or neurological infection. Most importantly, no tumorigenesis was found at a 2-year follow-up. The neurological functions, disability levels, and daily living abilities of the patients in this study were improved. While these observations support the use of the combination transplantation of NSPCs and MSCs as a safe and feasible method of improving neurological function, further studies that include larger samples, longer follow-ups, and control groups are still needed. This manuscript is published as part of the International Association of Neurorestoratology (IANR) special issue of Cell Transplantation.

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